Cologne was the filmmaker's main focus for a long time. But his latest work goes beyond the city limits: "Das alte Rheinland in Farbe" (The old Rhineland in colour) describes the most German of all rivers from Cologne to Mainz. Bonn plays a major role in the historical journey. The DVD consists of a total of 800 film scenes.

The oldest film clips are 127 years old, the "youngest" are from the 1950s, and the special highlight is that the over 800 black and white film scenes have been colourised. Hermann Rheindorf: " We've already done this with other DVDs. But this time, the elaborate process has been x^improved by the use of AI."

And so people, castles, ships and marketplaces are colourfully enhanced. All the scenes in the 80-minute film are first put in the required order - still in black and white. Each sequence is scrutinised for any image errors. This is because the scenes are of different origins and thus of different quality.

In the next step, a so-called "reference image" is selected for each film section. This is coloured by the AI, which has been fed a wealth of data, and then used as a template for the entire sequence. The filmmaker: "Afterwards, the coloured version is checked again for errors and reworked." (80 minutes of film correspond to 120,000 individual shots.)

Bonn was one of the richest cities in Germany around 1910, and Rheindorf found plenty of material about it in the private collections of former amateur filmmakers, archives and libraries. This was even though there was not a lot of industry based in Bonn. One spectacular example is the footage of President Paul von Hindenburg's visit in 1926 when he appeared on the steps of the historic town hall to cheering crowds after visiting the university.

Of course, there are shots of the Beethoven monument in the documentary. After that, there is a detour into the surrounding area to the funicular railway that leads up the Drachenfels and to the Rolandsbogen. The view of the Rhine Valley from up there was once described by the well-travelled explorer Alexander von Humboldt as "the seventh most beautiful view in the world."

But there are even more spectacular shots: Winegrowers harvesting grapes, pilots manoeuvring large tugboats safely through the narrowest parts of the Rhine and a huge wooden raft drifting downstream. Additional historical information is added to the film sequences. It's not a bit boring, because Rheindorf has once again succeeded in enlisting star voice actor Christian Brückner, familiar to German-speakers as the German voice of Robert de Niro, Warren Beatty and Robert Redford, as commentator.

(Original text: Christof Ernst / Translation: Jean Lennox)